Évançon

The stream has its origin in the Great Glacier of Verra at the top of the val d'Ayas. After coursing right through the valley, the Évançon flows into the Dora Baltea in the comune of Verrès, near the bridge of Fleuran. From source to valley floor it crosses four municipalities: Ayas, Brusson, Challand-Saint-Anselme, and Challand-Saint-Victor. Near Targnod in the commune of Challand-Saint-Victor, the stream dashes into the Gorge de Brisecou (French for "Breakneck Gorge"), forming the impressive rapids of that name. Its base can be reached by a short walk from the road to Isollaz and a good observation spot can be reached by car on the road which leads to Verrès Castle.

The Évançon is a typical glacial river, which means that maximum flow is reached in the summer on account of the melting of the glacier and minimum flow occurs in winter - the opposite of other rivers. The colour of the water in the stream varies from azure in the morning and when it is cold through to a grey-white towards the evening and after a very hot day. Only in the winter is the river transparent, while in the summer it is more or less clouded by sediment and sand from the glacier.

The stream is inhabited exclusively by trout (both brown and rainbow, repopulated annually by the regional fish consortium. Among the wildlife must be mentioned the white-throated dipper which is present in great numbers.

To protect the inhabited area of the plain which has suffered from flooding in the past, protective walls have been built. Unfortunately, in addition to harming the naturalness and aesthetic appearance of the stream, these have made it less hospitable to the trout.

Along its course the stream is used to produce hydroelectric power. In the comune of Brusson, is found the Isollaz dam which extracts power from the river.[1]